Cardiac operations are increasingly commonplace, and usually necessary, given the critical contribution cardiac health makes to a person's well being and survival. It is also recognized, however, that the invasive nature of cardiac procedures, whether they involve implantation of a cardiac device such as a pacemaker or valve repair, has the potential to produce post-surgery stress responses. For example, arrhythmias following cardiothoracic surgery are thought to result from direct mechanical irritation of the pericardium or myocardium, and due to increased sympathetic and hormonal activity. In another example, the use of cardiopulmonary bypass is considered to be linked to systemic inflammatory responses.
Some known approaches to monitoring cardiac health after surgery use implanted cardiac sensors. Wired sensors, however, require passage of wires through cutaneous layers, thereby risking physical injury and infection. Wireless sensors are hence more desirable for such biological operation. Implantation of sensors, however, is an invasive procedure by itself, which elevates and contributes to the risk faced by the patient. There is hence a need for sensors and sensor systems that reduce or otherwise minimize the additional risk associated with sensor-based monitoring of cardiac health after surgery and/or after implantation of a cardiac device.